Creating a run/debug configuration

In the Run/Debug Configuration dialog box, click on
the toolbar or press Alt+Insert.
The drop-down list shows the default run/debug configurations. Select the desired configuration type.

The fields that appear in the right pane, display the default settings for the selected
configuration type.

If you want to change the settings of the default run/debug configuration,
expand the Defaults node, select the desired configuration type, and modify it as
required.

For the new run/debug configuration:

Specify its name in the Name text box. This name will be shown in the list of the
available run/debug configurations.

Specify whether you want to make WebStorm check execution status of
the instances of the same run/debug configuration. If you want to make sure that only one instance
of the run/debug configuration is currently executed, select the check box
Single instance only. In this case, a confirmation dialog box will show up
every time you try to launch run/debug configuration, when one instance of the same type is still
running.

If you click OK in the confirmation dialog box, the first instance of the
runner will be stopped, and the next one will take its place.

If this check box is not selected, you can launch as many instances of the runner as required.
As the result, each runner will start in its own tab of the Run tool window.

To use an existing configuration as a pattern, create its copy
by clicking the Copy button on the toolbar,
then change it as required.

In the
Before launch section, define whether you want to
execute some tools or scripts prior to launching the run/debug configuration.